This invention relates generally to improvements in oil seal rings and more particularly to those for reciprocating and rotary piston internal combustion engines and to methods of making such rings.
As is well known, oil seal rings of the character described are principally intended to prevent intrusion of any excess of lubricating oil into the combustion chamber of the engine and in use are moved slidingly along the inside wall surface of the associated cylinder of a reciprocating piston combustion chamber or of the side housing of a rotary piston combustion engine, as the case may be, to scrape down any excess of lubricating oil lying on the surface. In order that such oil seal ring may maintain its oil scraping performance at a satisfactory level for any extended period of service, it is desirable that the oil scraping edge of the ring be held at all times acute enough to make line contact with the associated wall surface of the engine for efficient oil scraping. In fact, however, oil seal rings and particularly those used in a rotary piston engine are subjected to complex external forces and thus forced to make complicated movements. This causes a considerable frictional wear of the ring and which in the past has resulted in substantial loss in acuteness and hence in oil scraping effect of the ring edge held in sliding contact with the engine wall surface and thus has caused increase in lubricant oil consumption of the engine. Further, as wear of the ring proceeds, the area of the ring surface contacting with the engine wall surface increases and this has previously resulted in reduction in pressure of contact therebetween and hence in impairment of the oil scraping effect of the oil seal ring.